Thanks to David Joyner for his response to my original question. His method worked nicely. Incidentally, here is the original Maple code from the lecture of Doron Zeilberger that I was trying to translate into Sage:
with(combinat): P:=(d,x,y)->add(add(a[i,j]*x**i*y**j,i=0..d- j),j=0..d); V:=d->fseq(seq(a[i,j],i=0..d-j),j=0..d)g; E:=d->fseq(P(d,fibonacci(n),fibonacci(n+1)),n=1..nops(V(d))+5) g: Q:=(d,x,y)->subs(solve(E(d),V(d)),P(d,x,y)); These lines feature the sort of indexed variables a[i,j] discussed above. (The full lecture from which I took these lines can be found at http://www.math.rutgers.edu/~zeilberg/mamarim/mamarimhtml/em.html.) Here is a variant on the original question: suppose I wanted to write a line that creates a polynomial ring whose variables are a_{ij} for i +j<=d. How should I do it? I might want to set this up, for example, so that I could tell Sage about an algebraic group action on the space of polynomials of degree <=d. For a simpler variant: is there a convenient way to construct QQ[x_{ij}] with 1\leq i,j\leq n? I am a overwhelmed with the various ways to construct a polynomial ring, and so I cannot tell if one of them would be appropriate for this purpose. I can see how to make a polynomial ring in n^2 variables, but I do not know how to name them x_{ij}. Thanks again for your help, James Parson --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
